001 /**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.camel.processor;
018
019 import java.util.Collection;
020 import java.util.Iterator;
021 import java.util.List;
022
023 import org.apache.camel.AsyncCallback;
024 import org.apache.camel.AsyncProcessor;
025 import org.apache.camel.CamelContext;
026 import org.apache.camel.Exchange;
027 import org.apache.camel.Processor;
028 import org.apache.camel.Traceable;
029 import org.apache.camel.util.AsyncProcessorConverterHelper;
030 import org.apache.camel.util.AsyncProcessorHelper;
031 import org.apache.camel.util.ExchangeHelper;
032 import org.slf4j.Logger;
033 import org.slf4j.LoggerFactory;
034
035 import static org.apache.camel.processor.PipelineHelper.continueProcessing;
036
037 /**
038 * Creates a Pipeline pattern where the output of the previous step is sent as
039 * input to the next step, reusing the same message exchanges
040 *
041 * @version
042 */
043 public class Pipeline extends MulticastProcessor implements AsyncProcessor, Traceable {
044 private static final Logger LOG = LoggerFactory.getLogger(Pipeline.class);
045
046 public Pipeline(CamelContext camelContext, Collection<Processor> processors) {
047 super(camelContext, processors);
048 }
049
050 public static Processor newInstance(CamelContext camelContext, List<Processor> processors) {
051 if (processors.isEmpty()) {
052 return null;
053 } else if (processors.size() == 1) {
054 return processors.get(0);
055 }
056 return new Pipeline(camelContext, processors);
057 }
058
059 public void process(Exchange exchange) throws Exception {
060 AsyncProcessorHelper.process(this, exchange);
061 }
062
063 public boolean process(Exchange exchange, AsyncCallback callback) {
064 Iterator<Processor> processors = getProcessors().iterator();
065 Exchange nextExchange = exchange;
066 boolean first = true;
067
068 while (continueRouting(processors, nextExchange)) {
069 if (first) {
070 first = false;
071 } else {
072 // prepare for next run
073 nextExchange = createNextExchange(nextExchange);
074 }
075
076 // get the next processor
077 Processor processor = processors.next();
078
079 AsyncProcessor async = AsyncProcessorConverterHelper.convert(processor);
080 boolean sync = process(exchange, nextExchange, callback, processors, async);
081
082 // continue as long its being processed synchronously
083 if (!sync) {
084 LOG.trace("Processing exchangeId: {} is continued being processed asynchronously", exchange.getExchangeId());
085 // the remainder of the pipeline will be completed async
086 // so we break out now, then the callback will be invoked which then continue routing from where we left here
087 return false;
088 }
089
090 LOG.trace("Processing exchangeId: {} is continued being processed synchronously", exchange.getExchangeId());
091
092 // check for error if so we should break out
093 if (!continueProcessing(nextExchange, "so breaking out of pipeline", LOG)) {
094 break;
095 }
096 }
097
098 // logging nextExchange as it contains the exchange that might have altered the payload and since
099 // we are logging the completion if will be confusing if we log the original instead
100 // we could also consider logging the original and the nextExchange then we have *before* and *after* snapshots
101 LOG.trace("Processing complete for exchangeId: {} >>> {}", exchange.getExchangeId(), nextExchange);
102
103 // copy results back to the original exchange
104 ExchangeHelper.copyResults(exchange, nextExchange);
105
106 callback.done(true);
107 return true;
108 }
109
110 private boolean process(final Exchange original, final Exchange exchange, final AsyncCallback callback,
111 final Iterator<Processor> processors, final AsyncProcessor asyncProcessor) {
112 // this does the actual processing so log at trace level
113 LOG.trace("Processing exchangeId: {} >>> {}", exchange.getExchangeId(), exchange);
114
115 // implement asynchronous routing logic in callback so we can have the callback being
116 // triggered and then continue routing where we left
117 //boolean sync = AsyncProcessorHelper.process(asyncProcessor, exchange,
118 boolean sync = asyncProcessor.process(exchange, new AsyncCallback() {
119 public void done(boolean doneSync) {
120 // we only have to handle async completion of the pipeline
121 if (doneSync) {
122 return;
123 }
124
125 // continue processing the pipeline asynchronously
126 Exchange nextExchange = exchange;
127 while (continueRouting(processors, nextExchange)) {
128 AsyncProcessor processor = AsyncProcessorConverterHelper.convert(processors.next());
129
130 // check for error if so we should break out
131 if (!continueProcessing(nextExchange, "so breaking out of pipeline", LOG)) {
132 break;
133 }
134
135 nextExchange = createNextExchange(nextExchange);
136 doneSync = process(original, nextExchange, callback, processors, processor);
137 if (!doneSync) {
138 LOG.trace("Processing exchangeId: {} is continued being processed asynchronously", exchange.getExchangeId());
139 return;
140 }
141 }
142
143 ExchangeHelper.copyResults(original, nextExchange);
144 LOG.trace("Processing complete for exchangeId: {} >>> {}", original.getExchangeId(), original);
145 callback.done(false);
146 }
147 });
148
149 return sync;
150 }
151
152 /**
153 * Strategy method to create the next exchange from the previous exchange.
154 * <p/>
155 * Remember to copy the original exchange id otherwise correlation of ids in the log is a problem
156 *
157 * @param previousExchange the previous exchange
158 * @return a new exchange
159 */
160 protected Exchange createNextExchange(Exchange previousExchange) {
161 return PipelineHelper.createNextExchange(previousExchange);
162 }
163
164 protected boolean continueRouting(Iterator<Processor> it, Exchange exchange) {
165 boolean answer = true;
166
167 Object stop = exchange.getProperty(Exchange.ROUTE_STOP);
168 if (stop != null) {
169 boolean doStop = exchange.getContext().getTypeConverter().convertTo(Boolean.class, stop);
170 if (doStop) {
171 LOG.debug("ExchangeId: {} is marked to stop routing: {}", exchange.getExchangeId(), exchange);
172 answer = false;
173 }
174 } else {
175 // continue if there are more processors to route
176 answer = it.hasNext();
177 }
178
179 LOG.trace("ExchangeId: {} should continue routing: {}", exchange.getExchangeId(), answer);
180 return answer;
181 }
182
183 @Override
184 public String toString() {
185 return "Pipeline[" + getProcessors() + "]";
186 }
187
188 @Override
189 public String getTraceLabel() {
190 return "pipeline";
191 }
192 }